منابع مشابه
s-Degrees within e-Degrees
For any enumeration degree a let D a be the set of s-degrees contained in a. We answer an open question of Watson by showing that if a is a nontrivial Σ2-enumeration degree, then D a has no least element. We also show that every countable partial order embeds into D a.
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We consider a random graph process analogous to one suggested by Barabási and Albert. Their model can be roughly described as follows. At each step we add one vertex and one outgoing edge, and the probability that the new vertex is connected to a vertex v is proportional to the degree of v. These types of processes serve as models of real-world networks. In this paper we consider a well-known g...
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We say that A ≤LR B if every B-random set is A-random with respect to Martin-Löf randomness. We study this reducibility and its interactions with the Turing reducibility, Π1 classes, hyperimmunity and other recursion theoretic notions. A natural variant of the Turing reducibility from the point of view of Martin-Löf randomness is the LR reducibility which was introduced in [12]. We say that A ≤...
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The high/low hierarchy respects the ordering of degrees, and so we can expect to find properties of order which are possessed by all degrees in a given hierarchy class. Such properties can also be found for classes of the generalized high/low hierarchy even though that hierarchy does not respect the ordering of the degrees. For example, Jockusch and Posner [4], extending a result of Cooper [l],...
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ژورنال
عنوان ژورنال: British Dental Journal
سال: 2010
ISSN: 0007-0610,1476-5373
DOI: 10.1038/sj.bdj.2010.302